Put limit on search depth for finding source variables for derivation
Put limit on search depth for finding source variables for derivation

The limit is now 16 steps deep for allowing sources of a derivation to be again provided via a derivation.
Allowing an unlimitted depth resulted in excessively long searches for specific derivations.

stcorp/harp,stcorp/harp,stcorp/harp,stcorp/harp,stcorp/harp,stcorp/harp